Melon Postharvest Diseases Occurrence And The Selection Of Biocontrol Yeast

Melon is a kind of popular and highly nutritional fruit. The severe problem for the melon production is post-harvest diseases caused by pathogenic. For the lacking of powerful and harmless control ways, the biological control emerges as a promising way to solve this problem.In our study, strains b3,b6,b8,b1,b13,b21 and b49 were isolated from the surface of disease melon. The b3,b6,b8,b1,b13 and b21 strains were caused the melon post-harvest diseases were identified as Phoma putaminum,Fusarium oxysporm , Penicillium italicum, Alternaria tenuis , Trichothecium roseum ,Curvularia lunata and Fusarium equiseti separately based on their rDNA-ITS sequence,the morphological characterization, culturing pattern, and physiological and biochemical reactions.Yeast strains x6 and p2 were isolated from the surface of healthy melon. Bioassay results showed that the strains x6 and p2 could strongly protect the melon fruits from infection by Fusarium spp. and the inhibition rate is 59 % and 51% separately. The strains x6 and p2 were identified as Pichia anomala and Rhodotorula glutinis according to their rDNA-ITS sequence, morphological characterization, culturing pattern, and physiological and biochemical reactions. The inhibition experiments results suggested that the biocontrol yeast strains x6 and p2 give a very clear effects on the control of melon post-harvest diseases both in the field trail and also in the laboratory condintions. The strain x6 has the stable and equal effect to chemical fungicide.The biocontrol mechanism of yeast strains x6 and p2 to the post-harvest diseases was also studied in our project.The preliminary results revealed that the both of the yeast strains growed well on the peels of melon. When the melon were soaked in the two yeast cell suspensions of 1×108CFU/mL, the activities of phenlalanine ammonialyase (PAL) and peroxidase in fruits of melon raised remarkably, while polyphenol oxidase (PPO) reduced prominently.